The present invention relates to hot melt glue binding, and more particularly concerns such binding which offers maximum adaptability and flexibility in home or office preparation of the front cover and thickness of bound documents.
Presently known glue binders for home or office use generally employ pre-formed front and back covers having a spine or backbone bearing hot melt glue, or provide only a glue bearing spine strip. Typical of such binders are the arrangements illustrated in U.S. Pat. Nos. 4,371,194 to Wang, et al, 4,471,976 to Giulie, 4,129,471 to Rome, and 4,496,617 to Parker. The Parker patent employs only a backbone strip having bands of hot melt glue adapted to cover and connect to the back edges of the sheets to be bound and also has hot melt glue bands that are adapted to be secured to the topmost and bottommost sheets of the stack, which then serve as front and back cover sheets of the bound volume. The arrangements of the Wang et al, Giulie and Rome patents, on the other hand, provide binders having complete front and back covers which form the outer covers of the completed bound document. Of these, the patent to Wang et al provides for variable thickness of bound documents by providing a variable width foldable spine. If the spine is folded to accept a smaller stack of documents, one of the covers inherently becomes wider, and thus Wang et al must provide for folding of a cover end remote from the spine, to eliminate this increase in cover width and to obtain a more regular finished document.
A major drawback of the arrangements of Rome, Wang et al and Giulie is that the cover sheets are an integral part of the binder, and there is thus little flexibility in choice of cover or in ability to process the cover. The patent to Parker addresses this problem by providing no covers for the binder but rather arranging the spine with several spaced bands of precisely configured and positioned hot melt glue so that a central glue band will adhere to and bind back edges of the document, and two additional side glue bands on either side of the central band will simultaneously adhere to the top and bottom sheets of the stack of documents being bound. The glue is conventional hot melt adhesive, and thus the entire stack, including the top and bottom sheets which form front and back covers, must be bound together, all at the same time. A more significant problem with the arrangement of Parker, which is discussed at length in the patent itself, is the difficulty of ensuring that the binder strip, or substrate, which carries the hot melt glue will adequately and properly adhere to the top and bottom sheets. The Parker binder requires precision manufacturing with small tolerances of glue strip thicknesses and gaps, and moreover, after manufacturing can fit only one thickness of document which must be precisely matched to the size of the Parker binder strip. In the arrangement of Parker, in order to ensure proper adhesion of the binder strip to the cover, it is essential to carefully control the location and thickness of the glue bands and the gaps between the various glue bands. Failure to meet these precise requirements results in a poor and unacceptable binding. Moreover, the Parker system requires a special, complex and costly machine capable of heating and pressing the spine and both sides of the binder. Thus Parker is not really an in-home or office system.
Accordingly, it is an object of the present invention to provide a hot melt glue binder for home or office use that avoids or minimizes above-mentioned problems.